JPH1114533A - Particulate shape measuring instrument - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an instrument which successively obtains two-dimensional sectional images of a particulate while continuously changing the direction of the particulate to obtain the two-dimensional sectional images of the particulate at different angles. SOLUTION: The particulate flows in a tube 10 having an observation window 20. The particulate in the tube 10 is lightened up by a light source 80, its image is photographed by a television camera 60, and the image data are recorded in a control analyzing device part 70. Ultrasonic-wave vibrators 30 and 31 are arranged on two adjacent wall surfaces of the tube 10 and waveforms having voltage amplitudes which are generated by a waveform synthesizer 40 are amplified by amplifies 50 and 51 under the command of the control analyzing device part 70 and then inputted to the ultrasonic vibrators 30 and 31. The ultrasonic-wave vibrators 30 and 31 generate mutually orthogonal plane standing waves in the tube, and the plane standing waves orient the particulate on the minimal planes of the position potentials of the standing waves generated with their wave fronts.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for measuring the shape of fine particles in a solution using ultrasonic radiation pressure or ultrasonic flow phenomenon and image processing technology.

[0002]

2. Description of the Related Art Particle size measurement for estimating the size of fine particles such as powder is an essential technique for evaluating quality such as the uniformity of powder particles. When the specific gravity of the fine particles is known, the particle diameter can be estimated from the sedimentation speed of the fine particles using a liquid phase sedimentation method. Alternatively, the Brownian motion of the fine particles is optically observed, for example, the diffusion constant of the fine particles is obtained from the Doppler displacement of the wavelength of the scattered light, and the particle size distribution of the fine particles can be obtained therefrom. In addition, when the optical refractive index of the fine particles is known, since the intensity of the scattered light of the fine particles changes depending on the particle size, it is possible to estimate the particle size distribution of the fine particles from the distribution of the scattered light intensity. it can.

However, according to the above-described method, only the equivalent circle diameter of the fine particles can be obtained, and fine particles such as living cells having substantially the same average particle size and no large difference in composition are classified. Had insufficient information. Therefore, a technology for recognizing abnormalities in living cells was developed by directly recording and analyzing the image of fine particles in a solution using image recognition technology. When it is not possible to recognize the type, it has been found that it is difficult to recognize the type of the fine particles using the image processing technology. Therefore, at present, a `` flow-type particle image analyzer '' that creates a laminar flow, introduces a solution containing fine particles into it, and acquires an image of the fine particles while orienting the long axis direction of the fine particles in a specific direction, Image analysis technology is becoming mainstream.

[0004] Orientation of the fine particles can be realized by applying some non-contact force to the fine particles in addition to applying the hydrodynamic contact force as described above. Examples of the non-contact force include Coulomb force due to an electrostatic field, magnetic force due to a static magnetic field, radiation pressure of light, radiation pressure of ultrasonic waves, and the like.
Regarding the radiation pressure applied to the particles when the ultrasonic waves are applied to the particles, for example, Jonle Bourg describes in Journal of Acoustic Society of America No. 8
9 (1991), pp. 2140-2143 (J. Wu,
J. Acoust. Soc. Am. 89 (1991) pp. 2140-2143) reported that a 270 μm diameter polystyrene sphere was successfully captured at the focal point of focused ultrasound. Regarding the principle of capturing fine particles by the radiation pressure of ultrasonic waves, Yoshioka et al.
Years pp. 167-178 (K. Yosioka and Y. Kawasi)
ma, Acustica 5 (1955) pp. 167-178) calculate the magnitude of the ultrasonic radiation pressure applied to microparticles in standing waves and traveling waves in perfect fluid. Further, the inventors have disclosed in Japanese Patent Laid-Open No. 5-29.
As reported in Japanese Patent No. 6310, a method of introducing ultrasonic waves into a tube through which a fluid is flown to continuously focus fine particles in a certain range, or a method of collecting the focused fine particles has also been invented. And Japanese Patent Laid-Open No. 6-24197.
As reported in Japanese Patent Publication No. 7, a fine particle fractionating device for fractionating and collecting fine particles having different particle diameters and fine particles of different materials by combining the radiation pressure of ultrasonic waves and other external force such as an electrostatic field has also been invented. ing.

By applying ultrasonic radiation pressure to the fine particles, the fine particles can be rotated or oriented.
For example, by irradiating ultrasonic waves 90 degrees out of phase from two orthogonal sound sources, fine particles in the sound field start rotating, but MB Barmatz et al. Further describe in US Pat. No. 4,800,756 (1989). By adjusting the phase shift of the ultrasonic waves generated by the two orthogonal ultrasonic vibrators, the rotation speed of the fine particles in the sound field can be adjusted. Alternatively, it is reported that the direction in which fine particles having shape anisotropy are oriented can be adjusted.

It is considered that the ultrasonic flow phenomenon in which a liquid flows by irradiating an ultrasonic wave to a liquid itself is caused by a gradient of ultrasonic intensity. It is only necessary to increase the power density or increase the attenuation of the ultrasonic wave in the fluid. The flow phenomenon caused by surface acoustic waves (SAW) is also described by Shiokawa et al. In Japanese Journal of Applied Physics, Vol. 29 (1990), pp. 135-137.
(S. Shiokawa et al., Jpn. J. Ap
pl. Phys. Supl. 29-1 (1990) pp. 135-137). This is a phenomenon that the Rayleigh SAW created on the substrate surface by the comb-shaped electrode becomes a leaky SAW that is a radiation mode into water at the water / solid interface, whereby the water droplets dropped on the substrate flow or fly. It is.

As a method for generating a SAW, an inter digital transducer (ID) is mainly used.
T) and a method of converting a bulk wave into a surface wave. The method using IDT is generated by crossing electrodes in a comb shape on a piezoelectric substrate and applying an AC voltage to these electrodes. In this case, the interval between the comb electrodes is desired to be used. 1/2 of the wavelength (λ) of the ultrasonic wave
(Ie, λ / 2), and the electric field that can be applied to the comb electrode is limited to 4 kV / cm, so it is difficult to generate strong ultrasonic waves with low frequency ultrasonic waves.

A method of converting a bulk wave into a surface wave is a method of converting a bulk wave such as a strong ultrasonic wave into a surface wave by using a previously established bulk wave generating means. For example, using a prism-shaped solid, a prism coupler method for generating SAW from a leaky wave at the boundary surface of a bulk wave, or a periodic structure on a solid surface for generating SAW,
A grating coupler method for generating a SAW by applying a bulk wave to this is disclosed by Humphries et al. In Electronics Letter, Vol. 5 (1969), No. 175.
Pages 176 to 176 (RF Humphryes an
d EA Ash, Electronics Lett.Vol. 5 (1969) pp.17
5-176).

[0009]

SUMMARY OF THE INVENTION Among the above prior arts,
Since the flow type particle image analyzer is a technique utilizing the orientation of fine particles in a laminar flow, it is easy to take a two-dimensional cross-sectional image of the cross section when the fine particles are oriented in a specific direction. Yes, but to get a three-dimensional image of the particles,
It was difficult to control the orientation direction of the fine particles and to take a plurality of two-dimensional cross-sectional images obtained from different angles. Further, in order to utilize the torque generated in the laminar flow, it is necessary to flow the solution at a certain flow rate or higher, and special measures are required for the shape of the container through which the fluid flows.

According to the present invention, a two-dimensional cross-sectional image of a fine particle is continuously obtained while continuously changing the direction of the fine particle flowing continuously in a pipe, regardless of the flow velocity of the fluid containing the fine particle. It is an object of the present invention to provide a device for acquiring two-dimensional cross-sectional images from different angles.

[0011]

In order to achieve the above object, a fine particle shape measuring apparatus according to the present invention introduces an ultrasonic standing wave into a pipe through which fine particles flow in a direction perpendicular to the flow of fluid in the pipe. Means, means for continuously changing the shape of the position potential distribution created by ultrasonic waves, and means for continuously obtaining a two-dimensional cross-sectional image of the fine particles in the tube according to the change in the position potential distribution And More specifically, a plane standing wave is generated in two different directions in a tube, and the intensity ratio of the generated ultrasonic radiation pressure is changed over time to change the direction in which the fine particles are oriented over time. You only need to change it.

[0012] Alternatively, in order to achieve the above object, the fine particle shape measuring apparatus of the present invention uses an ultrasonic wave to generate an acoustic stream having a certain rotational direction in a direction perpendicular to the flow of a solution containing fine particles in a tube. It has means for creating a vortex and continuously rotating fine particles in the fluid by the rotation of the vortex, and means for continuously obtaining a two-dimensional cross-sectional image of the fine particles in the tube according to the change. More specifically, a means for introducing ultrasonic waves into the tube from a part of one wall surface of the tube wall and a wall facing the sound source having a certain angle may generate a vortex in the tube. . Alternatively, when a plurality of ultrasonic sound sources are arranged in a fan shape on the outer wall of a cylindrical tube, and the phase of the ultrasonic wave generated by each ultrasonic vibrator makes one round around the tube,
A phase shift may be generated so that the 2nπ phase shifts. Here, n is an integer. Alternatively, by generating an ultrasonic elastic wave on the inner wall surface of the pipe, a vortex derived from an ultrasonic flow phenomenon may be generated near the pipe wall.

[0013]

FIG. 1 is a schematic diagram of a first embodiment of the present invention. In this embodiment, the orientation direction of the fine particles is controlled by combining two orthogonal potential surfaces created by two orthogonal plane standing waves created in the tube. The fine particles whose shape is to be observed flow through the tube 10 having the observation window 20. The fine particles in the tube are illuminated by the light source 80, an image of the fine particles is taken by the television camera 60, and the image data is recorded in the control analysis unit 70. In order to control the direction in which the fine particles are oriented, ultrasonic vibrators 30 and 31 are arranged on two adjacent wall surfaces of the tube 10 through which the solution containing the fine particles continuously flows. , The waveform of the voltage amplitude generated by the waveform synthesizer 40 is
After being amplified at 0 and 51, they are introduced into the ultrasonic transducers 30 and 31. Ultrasonic transducers 30, 3
1 can generate plane standing waves orthogonal to each other in the tube, and each plane standing wave can orient the fine particles on the minimum surface of the position potential of the standing wave generated by the wave front.

FIG. 2 schematically shows the actual rotation of the fine particles in the apparatus of the present invention shown in FIG. FIG. 2 (a)
The fine particles 101 flowing in the tubes 91 and 92 as shown in FIG.
Along the flow of the sample solution, it proceeds downstream while rotating as indicated by arrow 111. At this time, as shown in FIG. 2B, when the ultrasonic irradiation intensity of the ultrasonic oscillator 30 is strong, the ultrasonic irradiation intensity of the ultrasonic oscillator 31 is weak, and the ultrasonic irradiation intensity of the ultrasonic oscillator 30 is low. By changing the ratio of the ultrasonic irradiation intensity continuously so that the ultrasonic irradiation intensity of the ultrasonic oscillator 31 is strong when the ultrasonic oscillator 31 is weak, the fine particles are adjusted according to the ratio of the ultrasonic intensity irradiated from each ultrasonic oscillator. By changing the orientation of the fine particles, the rotation of the fine particles as shown in FIG. 2A can be realized. That is, by continuously reducing the ultrasonic intensity of the ultrasonic vibrator 30 and increasing the ultrasonic intensity of the ultrasonic vibrator 31 from the state of the image A in which the fine particles 101 are horizontally oriented, the fine particles The direction is changed as indicated by an arrow 112 while flowing through the tube, and a vertically oriented image (image B) can be observed like the fine particles 102. When an image of fine particles is continuously or fragmentarily acquired by a television camera, the ultrasonic transducers 30, 3
By referring to the ultrasonic irradiation intensity ratio of 1, the orientation direction of the fine particles can be simultaneously estimated. In addition, one
The rotation time is desirably while the particles are within the field of view of the television camera. Therefore, it is necessary to adjust the speed of change of the ultrasonic intensity of the ultrasonic transducer according to the flow velocity.

FIG. 3 is a schematic diagram of a second embodiment of the present invention. This example was created in a tube by ultrasound,
The fine particles are rotated by a vortex of the solution orthogonal to the flow of the solution containing the sample. Tube 12 with observation window 121
During 0, the solvent flows in the directions of arrows 141 and 142.
A sample liquid containing fine particles is introduced from the tube 151 into the center of the tube. Ultrasonic vibrators 131 and 132 are respectively disposed on a part of two opposite surfaces of the tube, and rotation of the fluid in the tube is caused by an acoustic stream generated by ultrasonic waves introduced from these ultrasonic vibrators. Occur. FIG. 4 is a sectional view of the tube 120 taken along the line AA. Each ultrasonic transducer 131,
The wall surface in the tube facing 132 has a certain angle with respect to the ultrasonic vibrator, and the ultrasonic wave reflected by this wall returns to the sound source direction so that a standing wave is not generated. ing. The traveling wave of the ultrasonic wave generated by such a configuration causes rotation of the solution containing the fine particles 17.
0 occurs and the fine particles 160 rotate while flowing in the tube.

FIG. 5 is a sectional view of a third embodiment of the present invention as viewed from a section perpendicular to the flow of the pipe. In the present embodiment, FIG.
As in the case of the second embodiment shown in (1), the fine particles are rotated by a vortex of the solution orthogonal to the flow of the solution containing the sample created in the tube by ultrasonic waves. The same effect as that of the above-described second embodiment can be obtained by adding a filler that reflects ultrasonic waves to the inner wall surface of the tube 122.

FIG. 6 is a sectional view of a fourth embodiment of the present invention as viewed from a section perpendicular to the flow of the pipe. In this embodiment, FIG.
As in the case of the second embodiment shown in (1), the fine particles are rotated by a vortex of the solution orthogonal to the flow of the solution containing the sample created in the tube by ultrasonic waves. An ultrasonic vibrator 135 is arranged on a part of one surface of the tube 124, and the ultrasonic wave is reflected in a direction having an angle, which is the inner surface of the tube, to generate a rotation 172 of the solution and generate fine particles 162. Rotates.

FIG. 7 is a sectional view of a fifth embodiment of the present invention as viewed from a section perpendicular to the flow of the pipe. In this embodiment, FIG.
As in the case of the second embodiment shown in (1), the fine particles are rotated by a vortex of the solution orthogonal to the flow of the solution containing the sample created in the tube by ultrasonic waves. Around the cylindrical tube 126 having the observation window 127, a plurality of fan-shaped ultrasonic transducers 1361, 1362, 1363, 1364, 136 are provided.
5, 1366 are arranged. Ultrasonic waves of the same intensity and frequency are emitted from each of these ultrasonic transducers, but when the phase of the ultrasonic waves emitted from each transducer is the angle at the tube surface of each transducer as θ, It is assumed that it is shifted by θ / 2nπ. Here, n is an integer. By driving the ultrasonic vibrator in this manner, the solution can be rotated as indicated by an arrow 173, and as a result, the fine particles 163 rotate. Further, in the present embodiment, the rotation of the fluid is used to rotate the fine particles. However, similarly to the first embodiment of the present invention, the ultrasonic vibrators 1361 and 1365 and 1362 and 1362 are used.
The particles can be rotated by changing the strength of the ultrasonic transducers 66 and 1363 with time.

FIG. 8 is a sectional view of a sixth embodiment of the present invention as viewed from a section perpendicular to the flow of the pipe. In this embodiment, a surface acoustic wave of ultrasonic waves is generated on the inner wall of the tube, and the fine particles are rotated by the vortex of the solution generated by the ultrasonic traveling wave that has permeated into the solution from the inner wall of the tube. Tube wall 191, 1
The surface acoustic waves travel in the directions of arrows 181 and 182 on the inner wall surface of the tube by the ultrasonic vibrators 137 and 138 attached to 93. This surface acoustic wave leaks into the solution, which causes rotation 174 of the solution and rotation of the fine particles 164. The rotating fine particles can be observed from the observation window 193. Similarly, as in the seventh embodiment shown in FIG. 9, a method for generating a surface acoustic wave on the inner wall of the tube is as follows.
A grating coupler method for converting ultrasonic bulk waves into surface acoustic waves may be used. Here, periodic grooves 195 and 196 are formed on the inner wall surfaces of the tube walls 194 and 197 where the surface acoustic waves are to be generated, and the ultrasonic oscillator 13
By irradiating ultrasonic bulk waves from 91 and 1392, surface acoustic waves are generated in the directions of arrows 183 and 184, and the fine particles 165 are rotated by the vortex 175 of the solution created by the surface acoustic waves leaking into the solution. .

[0020]

As described above in detail, by using the present invention, there is an effect that the shape can be continuously observed while continuously rotating the fine particles in the fluid.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a basic configuration of a first embodiment of the present invention.

FIGS. 2A and 2B are diagrams showing an operation of fine particles in a tube of the apparatus shown in FIG. 1, wherein FIG. 2A is a schematic diagram showing a state in which the fine particles flow while rotating in the tube, and FIG. The figure which shows the time-dependent change of the intensity | strength of the ultrasonic wave irradiated by the ultrasonic transducers 30 and 31 for the rotation of a microparticle as shown.

FIG. 3 is a schematic diagram showing a basic configuration of a second embodiment of the present invention.

FIG. 4 is a sectional view taken along the line AA of the embodiment shown in FIG. 3;

FIG. 5 is a sectional view taken along line AA of a third embodiment of the present invention.

FIG. 6 is an AA sectional view of a fourth embodiment of the present invention.

FIG. 7 is a sectional view taken along line AA of a fifth embodiment of the present invention.

FIG. 8 is an AA sectional view of a sixth embodiment of the present invention.

FIG. 9 is an AA sectional view of a seventh embodiment of the present invention.

[Description of References] 10, 120, 122, 124, 126 ... tube, 20, 121, 123, 125, 127 ... observation window, 30, 31, 131, 132, 133, 134, 13
5, 1361, 1362, 1363, 1364, 136
5, 1366, 137, 138, 1391, 1392 ...
Ultrasonic vibrator, 40: waveform synthesizer, 50, 51: amplifier, 60: television camera, 70: control analyzer unit, 80: light source, 91, 92: wall surface of tube 10, 101, 102, 160, 161, 162, 163, 1
64, 165: fine particles in a tube; 111, 112, 113: rotating direction of fine particles; 141, 142: flow of a solvent solution; 151: tube for introducing a sample solution 152 into a tube 120; 152: sample solution containing fine particles , 170, 171, 172, 173, 174, 175: rotating direction of the vortex of the solution, 181, 182, 183, 184: traveling direction of ultrasonic waves, 191, 192, 194: tube wall, 195, 196 ... cycle Grooves, 193, 197 ... glass, 201, 202, 203, 204 ... spacers.

Claims (6)

[Claims] 1. A tube through which a fluid containing fine particles flows, a means for introducing a standing wave of ultrasonic waves in a direction perpendicular to the flow of the fluid in the tube, and a shape of a position potential distribution generated by the ultrasonic waves in time. And a means for continuously acquiring a two-dimensional cross-sectional image of the fine particles in the tube according to the change in the potential distribution. 2. The method according to claim 1, wherein said ultrasonic sound source does not face the tube wall.
2. The fine particle shape measuring apparatus according to claim 1, further comprising means arranged on a surface, for changing the intensity ratio of the ultrasonic waves emitted from each sound source over time. 3. A tube through which a fluid containing fine particles flows and a flow of the fluid containing fine particles in the tube create an acoustic flow vortex having a certain rotational direction by ultrasonic waves in a direction perpendicular to the tube. A fine particle shape measuring apparatus comprising: means for continuously rotating fine particles in a fluid by rotation; and means for acquiring a two-dimensional cross-sectional image of fine particles in a tube in response to the rotation. 4. A means for introducing an ultrasonic wave into a part of at least one wall of the tube through which a fluid containing fine particles flows, and a wall facing the sound source is not parallel and has a predetermined angle. The particle shape measuring device according to claim 3, wherein: 5. A cross section of said pipe through which a fluid containing fine particles flows is cylindrical, a plurality of ultrasonic vibrators are arranged in a fan shape on an outer wall of the pipe, and a predetermined ultrasonic vibrator is used as a reference ultrasonic vibrator. Assuming that an angle between each ultrasonic transducer and the reference ultrasonic transducer is θ, an ultrasonic wave shifted by θ / 2nπ (n is an integer) according to an angle θ formed by the plurality of ultrasonic transducers. 4. The fine particle shape measuring apparatus according to claim 3, further comprising: means for generating each of the plurality of ultrasonic transducers. 6. An apparatus for measuring the shape of fine particles according to claim 3, further comprising means for introducing an ultrasonic surface acoustic wave to an inner wall surface of said tube through which a fluid containing fine particles flows.